Mass storage devices frequently require a number of sometimes diverse media to store a sufficient amount of data for certain applications. For example, corporate entities may create libraries of optical media and magnetic media to retain imaging files of purchase orders, invoices, and other forms for accounting purposes. To maintain such a library or other large data collections, it is frequently appropriate to utilize a media autochanger. Media autochangers provide a unitary structure to store a plurality of such diverse media, such as optical media, magnetic disks, tape cartridges, and/or the like. Media autochangers store the media in predefined locations within the unitary structure.
In operation, a media autochanger typically utilizes a drive unit and an associated drive train to physically move a media engaging component to the predetermined location associated with a media storage position when retrieval of the media is desired. After being translated to the appropriate position, the media engaging component may extend from a drive position to an engage position to retrieve the media. The media engaging component then retracts. The media engaging component with the retrieved media is transported to a media drive. Again, the media engaging component extends to place the media into the media drive. Of course, the reverse of this process occurs when it is desired to replace the media to its respective predetermined position.
It shall be appreciated that the steps associated with retrieving and replacing media require significant mechanical precision. Specifically, imprecise positioning may damage media or may cause the media autochanger to cease functioning. To properly position the media engaging component, media autochangers utilize a drive train feedback arrangement. In these configurations, various encoding mechanisms allow the media autochanger to determine how the drive train has been translated. By knowing the offset or translation of the drive train, the media autochanger may then estimate the position of the media engaging component. However, this approach is problematic. Specifically, physical characteristics of mechanical components frequently change with time. For example, the drive train may slip. Thus, the offset or translation of the drive train does not necessarily provide a completely accurate determination of the position of the media engaging component.
The present invention is directed to a system and method which utilize a feedback loop arrangement to control the accurate positioning of components. The system and method may utilize the feedback loop to control a component engaging member operable to retrieve a component. The feedback loop may control the component engaging member by activating a drive subsystem operable to translate the component engaging member. Additionally, the feedback control loop may implemented by utilizing a signal source operable to emit a signal and a signal receiver operable to receive the signal emitted by the signal source. The signal source and signal receiver are fixedly attached to the device. Also, the feedback loop may involve a processor operable to control retrieval of a desired component utilizing at least in part the signal emitted by the signal source and received by the signal receiver.